Automatic ladling device for vacuum die-casting machine



Sept 9, 1958 G. R. MoRToN lAU'IOMA'IC LADLING DEVICE FOR VACUUM DIE-CASTING MACHINE Filed Jan. 2o. 1958 INVENTOR, GLEN L MoRToN.

.Q\|1| l fr N. l lll lll 2332 v Uite AUTOMATIC LADLING DEVICE FOR VACUUM DIE-CASTING MACHINE This invention relates to vacuum die-casting machines, and more particularly it is an object of this invention to provide an automatic ladling device for such machines.

Heretofore automatic ladling devices have been primarily of the type which push the molten metal into the shot chamber. It is an object of this invention to provide an automatic ladling device which permits a preselected suiciently exact quantity of molten metal to be pushed into the shot chamber by atmospheric pressure in response to a pressure differential existing when a vacuum is drawn on the shot chamber and mold cavity.

A particular advantage is to provide an automatic ladling device which preserves the possibilities of more perfect castings of lesser porosity and greater speed of die-casting which are characteristic of a properly made vacuum die-casting machine.

Other ,and further objects and advantages of the present invention will be apparent from the following detailed description, drawing and claims, the scope of the invention not being limited to the drawing itself as the drawing is only for the purpose of illustrating a way in which the principles o-f this invention can be applied.

Other embodiments of the invention utilizing the same or equivalent principles may be used and structural changes may be made as desired by those skilled in the art without departing from the present invention and the purview of the appended claims.

In the drawing:

The single ligure of the drawing shows a cross section of a shot chamber of a die-casting machine, most other parts of the die-casting machine not being shown, the view further showing a cross section of an automatic ladling device of this invention.

The die-casting machine automatic ladling device of this invention is for use with a die-casting machine in which a vacuum is drawn on the shot chamber of the die-casting machine as indicated by an arrow 12 in the drawing prior to forward motion of the plunger 14 of the machine.

As the die-casting machine for use with this invention is in all 4other respects conventional, it is not shown in detail in the drawing.

The shot chamber 10 has an entrance opening 16 for molten metal disposed forwardly of the rearward position of the inner side of the plunger 14, which latter is the position shown in the drawing.

In accordance with this invention, the molten metal bath which is conventional on such machines is provided with a housing 24 having an upwardly opening piston cavity 26 which latter preferably has walls which are vertically disposed, the cavity 26 being cylindrical or otherwise. It is important, however, that a floating piston 30 of this invention loosely fits the walls of the cavity 26 so that the floating piston 30 can slidably move upwardly and downwardly in the cavity 26, the fit being sufficiently close as to suitably guide the motion of the floating piston 30 and yet being sufficiently loose, as best seen by the space existing at 34, to permit molten metal States Patent Patented Sept. 9, 1958 to flow into the bottom of the caviy 26 past the floating piston 30 at times when the floating piston 30 is moving upwardly in order that upward floating of the piston 30 is not hampered.

The housing 24 has a passage 36 extending through the housing from a passage entrance 38 at the inner end of the piston cavity 26 and extending to an outlet 44 at the exterior of the housing 24.

The housing 24 has a shoulder 46 at the inner end of the piston cavity 26 and at the point of junction with the passage 36 whereby the shoulder 46 functions as a valve seat in cooperation with the bottom surface of the oating piston 30 which latter is correspondingly shaped.

The shoulder 36 can be horizontal and the bottom of the valve-like floating piston 30 can also be horizontal and at, as shown, if desired.

A tube 50 interconnects the outlet end of the passage 36 and the entrance opening 16 of the shot chamber, the tube S0, the housing 24, and the floating piston 30 all being preferably formed of a ceramic material which is adapted to resist the heat of the molten metal.

The piston 30 can be constructed in many ways so as tooat on the molten metal 60 in the bath 20. When constructed as shown in the drawing the bottom part of the piston is of cylindrical shape having a hollow center 64 for effective oatation.

A lo-ng sleeve 66 extends vertically upward from and -is attached to the bottom cylindrical part of the piston andthe sleeve 66 is preferably formed of ceramic material as is the piston so as to protect an elongated threaded member 70 which is received and suitably attached to the interior of the sleeve 66, the elongated threaded member 70 extending upwardly through a nut 76 which is disposed on threads 7S which are placed at the upper end of the threaded member 70 above the sleeve 66.

The nut 76 is adapted to bear against the underside of a member S0 which latter has an aperture 82 extending upwardly therethrough for freely receiving the upper end of the elongated threaded member 70. The member 80 can be suitably attached by any suitable means to a stationary part of the machine for anchoring. Just by way of example, tabs 84 attached to member 80 are bolted by bolts 86 to a stationary part 90 of the machine, a part of which is shown in the drawing.

The passage 36 has a constricted portion indicated at which extends upwardly and preferably vertically in a position extending substantially co-extensive with the probable changes in level o f the molten metal 60 in the bath during operation. In this way the constricted portion 100 prevents the changes in level of the molten metal from unduly varying the quantity of metal in the shot, as it would unduly vary if the passage 36 were at full width in the area that is co-extensive with the changes in level of the molten metal in the bath.

As thus described, it will be seen that when, in the normal operation of the die-casting machine, the vacuum is drawn on the die cavity, not shown, and on the shot chamber 10, the metal which is disposed beneath the floating piston 30 will be pushed by the pressure diierential through the tube 50 into the shot chamber and continues until the piston 30 bottoms against the shoulder 46, which latter has the effect of shutting off further flow of molten metal.

As thus described it will be seen that adjustment of the nut 76 on the threaded member 78 controls the starting position of the floating piston 30 and the quantity of metal which enters the shot chamber in a single shot.

Such machines are timed so that the plunger 14 moves forwardly in a time sequence controlled by means not shown, and after the metal has entered the shot chamber 10 sufliciently, and whereby all metal beneath the piston 30 would have entered the shot chamber 10, whereupon the plunger 14 moves forwardly drivingthe molten metalv into the die cavity, not shown.

When the rearward end of the plunger 14 has passed the entrance opening 16 in the shot chamber then air can enter the tube 50 through the opening 16 since the plunger 14 is mounted on av plunger rod 120 which is of much lesser diameter than the interior of the shot chamber 10 allowing air to pass into the shot chamber and through the opening 16 by entering the shot chamber at its plunger opening 122.

The entrance of this air breaks the vacuum allowing the floating piston 30 to float upwardly until its positioning nut 76 strikes the bottom side of the stop member 80.

As thus described it will be seen that this invention provides an automatic ladling device for a vacuum diecasting machine which makes possible more swift ladling and which preserves the higher density and lesser porosity of the metal in the casting which is the chief advantage of the vacuum die-casting machine.

From the foregoing description, it is thought to be obvious that an automatic ladling device for vacuum diecasting machine constructed in accordance with my invention is particularly well adapted for use, by reason of the convenience and facility with which it may be assembled and operated, and it will also be obvious that my invention is susceptible of some change and modification without departingfrom the principles and spirit thereof, and for this reason I do not wish to be understood as limiting myself to the precise arrangement and formation of the several parts herein shown in carrying out my invention in practice, except as claimed.

I claim:

1. In combination with a die-casting machine of a type in which a vacuum is drawn on its shot chamber prior to forward motion of its plunger, said shot chamber having an entrance opening for molten metal disposed forwardly of the rearward position of said plunger, a molten metal bath, a housing in said bath having an upwardly opening piston cavity, said housing having a passage extending therethrough frorn an entrance at the inner end of said piston cavity to an outlet at the exterior of said housing, said housing having a shoulder at the inner end of said piston cavity and at the point of junction with said passage for functioning as a valve seat, a tube interconnecting the outlet of said passage with the entrance opening of said shot chamber, a piston so constructed as to float on said molten metal, said piston being slidably received in said piston cavity and moving into said cavity under the urge of atmospheric pressure when a vacuum is drawn through said tube, pasageway and cavity from said shot chamber, and means for preventing said piston from moving upwardly out of said cavity.

2. The construction of claim 1 in which said passage has an elongated constricted portion extending upwardly and substantially coextensive with the normal changes in level of the molten metal in said bath during operation for preventing such changes in level from unduly varying the quantity of metal in a shot.

3. The combination of claim 1 in which said means for preventing said piston from moving upwardly out of said cavity is adjustable and comprises an elongated threaded member having a nut attached thereto, means connecting said threaded member to said piston, and means anchored suitably to said machine and forming a stop above said nut and against which said nut engages.

References Cited in the le of this patent UNITED STATES PATENTS 

